With over 1,000 vessels operating throughout most of the global ocean, Taiwan is one of the world’s important fishing nations. One of the most lucrative species targeted is tuna, which is predominantly caught by longline fishing methods. Every year between 160,000-320,000 seabirds are killed as bycatch in longline fisheries globally.

A longline consists of a main line with thousands of baited hooks attached to it. The line can be relatively close to the sea surface and span up to 100km long. Seabirds, like albatross, can smell bait from up to 30km away and are attracted to the vessel. As the line is set into the water, the baited hooks are within diving range of the albatrosses, making them vulnerable to entanglement and drowning. 

However, effective methods to reduce seabird bycatch in pelagic longline fisheries exist. There are three main seabird bycatch mitigation methods:

  • Line weighting: weight is added close to every hook to increase the sink rate and take the hooks out of reach from diving seabirds faster.
  • Night setting: vessels set their line between nautical dusk and dawn. As most seabirds feed during the day, this reduces the likelihood of them being caught.
  • Bird-scaring lines: colourful streamers are suspended from a line towed behind the vessel to deter the seabirds from going near the hooks.

Line weighting is recognised as one of the most important mitigation measures, but to maximise the effectiveness of line weighting, it should be combined with bird-scaring lines (BSLs) and night setting.

Fishers onboard Taiwanese vessel trial - Wu Wun-huang

On the High Seas, which is all the ocean areas outside of country’s national waters, fishing is regulated by Regional Fisheries Management Organisations (RFMOs). Each of the five tuna RFMOs require members to annually report bycatch and to use two of the three best-practice seabird bycatch mitigation measures mentioned above in areas where seabirds are present.

The Taiwan Fisheries Agency requires Taiwanese vessels to use mitigation measures in areas overlapping with seabirds. Compliance with measures is monitored and recorded by onboard fisheries observers, who should be present on at least 5% of vessels. The information collected by observers is presented to relevant RFMOs to demonstrate compliance.

Whilst we have been working with RFMOs since 2004 to ensure seabird regulations are implemented, we recognise that collaborative work with fishers and observers is key to ensure good compliance, and therefore low seabird bycatch. By conducting port-based outreach work alongside the Taiwan Wild Bird Federation (TWBF) in Mauritius, we identified that BSLs were the preferred mitigation measure by Taiwanese vessels, yet many users felt design improvements could increase effectiveness.

Taiwanese vessels in port - Scott Pursner 

In 2020, the TWBF and the RSPB, in collaboration with the Taiwan Fisheries Agency, began work to improve the effectiveness of Taiwan’s BSLs by trialling the currently used configuration alongside a new design. Training was provided for observers to ensure consistency in data reporting, before two Taiwanese fishing vessels embarked on a fishing trip to the Indian Ocean.

“By working with the Taiwan Wild Bird Federation on this at-sea trial, we have been able to exchange knowledge and research improvements to bird scaring lines to achieve sustainable fisheries.”

The Taiwan Fisheries Agency

Observers Wu Wun-huang (left) and Andy Hsu (right), with Zhao Jun-yi from the Taiwan Fisheries Agency. 

“I felt honoured to participate in the bird scaring line trials. It is important to promote the effective use of bird scaring lines on Taiwanese fishing vessels and I hope that using bird scaring lines will enable fisheries to become more sustainable.”

Andy Hsu and observer aboard Yi Feng 826

“Participating in the trials required more effort than normal, but I learnt a great deal and intend to draw upon this experience and share with others in the future. It has raised awareness of reducing seabird bycatch amongst vessels workers in a way that has not happened before. I really hope an effective design for bird scaring lines can be created that works well with Taiwanese fishing operations.”

Wu Wun-huang and observer aboard Yi Feng 682

The vessels from the first trial returned in November 2021 and the data is now being analysed by Taiwanese researchers. A further three vessels recently completed a second trial for a new BSL design in the Pacific also. We hope the results will allow us to continue making improvements to the BSLs used by Taiwanese vessels to improve effectiveness of seabird bycatch mitigation measures and help protect important seabird populations.

Written in collaboration with Scott Pursner of the Taiwan Wild Bird Federation